2006 books
84) Daniel F. Galouye, Dark Universe, 1961
Probably something of a challenge to write, in that at least three quarters of this novel is set in absolute pitch black. As a post-apocalypse story of divided human societies forced to live below ground and where concepts of 'light' and 'darkness' have become nothing more than religious symbolism, I found it challenged me quite successfully to imagine a way of being that precluded sight, instead with enhanced hearing and the emerging development over generations of heat-sensitive vision. Galouye is not very well remembered now but Dark Universe was a decent enough start to a ten-year career of writing SF, which on the strength of this novel is probably worth looking further into.
skiffy word of the day
ziv (vt.): to see unaided with a visual sensitivity to heat, in the absence of light. (Also Zivvers, those who possess the evolved ability to see using thermal imagery).